World wide demand for hydrocarbons and related fertilizers and petrochemicals is increasing at a rapid annual rate. Crude petroleum and natural gas are basic in satisfying these demands but many industries have experienced shortages even though new oil and gas sources are being discovered. Therefore, alternate sources and feed stocks, such as coal, tar sands, oil shale and solid crudes are receiving greater consideration.
Tar sands, also known as oil sands and bituminous sands, are a particularly promising source of these needed products as large deposits are found in Canada and the United States. The largest deposits of the sands are the Athabasca sands found in northern Alberta, Canada where two commercial plants are in operation to recover synthetic oil from the sand. The Canadian tar sands underlay more than 13,000 square miles at a depth up to 2,000 ft. Of the 24 states in the United States that contain tar sands, about 90% of such deposits are in the state of Utah. The hydrocarbon resource locked in the Utah tar sands has been estimated to be in excess of 25 billion barrels. This presently untouched resource is quite significant when compared to the U.S. crude oil proven reserve of only about 31 billion barrels.
The demand for hydrocarbon resources makes development of Utah's tar sand virtually certain. However, the Utah tar sands, being of non-marine origin, have somewhat different chemical and physical characteristics than the Athabascan sands which are of marine origin, and do not respond as well to the process previously used to extract the oil from the tar sands. Utah tar sands are generally hard consolidated sand stone closely associated with petroliferous material (heavy viscous oil material) which is as high as 13% by weight with an average of 10.5% by weight. The oil is about 13.degree.-18.degree. API gravity and contains a low amount of sulfur, e.g. about 0.55% by weight, and low aromaticity.
The Utah tar sands also differ from the Canadian sands in that they have a very low water content. The Athabascan sand has an encapsulating water film surrounding each sand grain, which makes it amenable to a water-wetting process. The absence of this water film on the Utah sand grain necessitates using other technology for extracting the oils.
A comparison of the Athabascan tar sands with a sample of Utah tar sands obtained from Asphalt Ridge is shown in the following table:
______________________________________ Athabasca Sands Asphalt Ridge Sands ______________________________________ Carbon (wt-pct) 82.6 84.4 Hydrogen 10.3 11.0 Nitrogen .47 1.0 Sulfur 4.86 .75 Oxygen 1.8 3.3 Average Mol. Wt 568 820 (VPO-benzene) Viscosity (poise) 6,380 325,000 77.degree. F. (cone-plate at 0.05 sec Pct volatile material 60.4 49.9 (535.degree. C.) ______________________________________
The high viscosity, low sulfur content, low water content and other significant differences keep the Utah tar sands from responding well to known extraction processes.
A number of oil recovery methods related to oil shale and tar sands have been tested in the laboratory or in small operations in the filed. Examples of such prior known methods include those described in U.S. Pat. Nos. 4,218,304; 4,160,720; 4,199,432; 4,197,183; 3,440,162; 3,475,319 and 3,318,798. These processes involve various techniques such as hot water processes, cold water processes, solvent processes and thermal processes and the like, but in most cases, they possess certain limitations which make them unsuitable for use on a commercial basis with the Utah tar sands. A process which would be effective with these particular tar sands would be a significant advance in the art.
British Pat. No. 1,326,455 discloses a method for hydrotorting of shale to produce shale oil. However, in this case water is added to the reaction zone and this causes considerable difficulties including the need for large amounts of heat to remove the water at a later stage. In addition, they employ a slurry mix which adds to the difficulty of operation.
It is an object of the invention, therefore, to provide a new and efficient process for the extraction of hydrocarbonaceous material from solids containing such material and particularly from Utah tar sands. It is a further object to provide such an extraction process which could utilize equipment now in commercial use, meet present day EPA standards and could be rapidly put into commercial production to meet the urgent demand for hydrocarbon products.